Bga Package 18 Um Copper Wire Bonding Process

Because of the continuous increase of gold price, the copper wire process which replaces gold wire process developed rapidly in recent years. The copper wire has lower conductivity than gold wire. But in production, antioxidation process and parameter adjustment is needed as the copper wire is harder and easy to be oxidated.The BGA package had small size and fine finger pitch, and the chip inside evolves in the direction of much higher density and smaller pad pitch. Currently18um gold wire become to be more and more used. Therefore, to replacement the18um gold wire with20um copper wire is the trend for development.Firstly, the author introduced the assembly process flow of BGA package especially for the wire bonding process. Then the environment requirement was introduced as well as bill of material and machine list such as process requirement of cooper wire, some change of wire bonder and choice of capillary etc.Secondary, the author proposed for several test groups in use of the DOE method. He chose some parameter from experience, picked up the ones with biggest impact, and made a matrix of them. Based on this matrix of parameter, he got the results of several legs, input them into JMP in order to get optimized parameter range, verified the results and identified the range,evaluate the parameter at last, especially focus on the pad crack which is not often seen on bigger BPO pad.Finally, the reliability test was performed after process qualification. In the purpose of chip use, SQB test was selected and four items, procon, TC, THB and HAST, were included. Then the product passed all long term tests and the new process with18um copper wire is qualified.